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Spring Boot Configuration Processor
/*
* Copyright 2012-2018 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.boot.configurationprocessor.fieldvalues.javac;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
import javax.annotation.processing.ProcessingEnvironment;
import javax.lang.model.element.Modifier;
import javax.lang.model.element.TypeElement;
import org.springframework.boot.configurationprocessor.fieldvalues.FieldValuesParser;
/**
* {@link FieldValuesParser} implementation for the standard Java compiler.
*
* @author Phillip Webb
* @author Stephane Nicoll
* @since 1.2.0
*/
public class JavaCompilerFieldValuesParser implements FieldValuesParser {
private final Trees trees;
public JavaCompilerFieldValuesParser(ProcessingEnvironment env) throws Exception {
this.trees = Trees.instance(env);
}
@Override
public Map getFieldValues(TypeElement element) throws Exception {
Tree tree = this.trees.getTree(element);
if (tree != null) {
FieldCollector fieldCollector = new FieldCollector();
tree.accept(fieldCollector);
return fieldCollector.getFieldValues();
}
return Collections.emptyMap();
}
/**
* {@link TreeVisitor} to collect fields.
*/
private static class FieldCollector implements TreeVisitor {
private static final Map> WRAPPER_TYPES;
static {
Map> types = new HashMap<>();
types.put("boolean", Boolean.class);
types.put(Boolean.class.getName(), Boolean.class);
types.put("byte", Byte.class);
types.put(Byte.class.getName(), Byte.class);
types.put("short", Short.class);
types.put(Short.class.getName(), Short.class);
types.put("int", Integer.class);
types.put(Integer.class.getName(), Integer.class);
types.put("long", Long.class);
types.put(Long.class.getName(), Long.class);
WRAPPER_TYPES = Collections.unmodifiableMap(types);
}
private static final Map, Object> DEFAULT_TYPE_VALUES;
static {
Map, Object> values = new HashMap<>();
values.put(Boolean.class, false);
values.put(Byte.class, (byte) 0);
values.put(Short.class, (short) 0);
values.put(Integer.class, 0);
values.put(Long.class, (long) 0);
DEFAULT_TYPE_VALUES = Collections.unmodifiableMap(values);
}
private static final Map WELL_KNOWN_STATIC_FINALS;
static {
Map values = new HashMap<>();
values.put("Boolean.TRUE", true);
values.put("Boolean.FALSE", false);
values.put("StandardCharsets.ISO_8859_1", "ISO-8859-1");
values.put("StandardCharsets.UTF_8", "UTF-8");
values.put("StandardCharsets.UTF_16", "UTF-16");
values.put("StandardCharsets.US_ASCII", "US-ASCII");
WELL_KNOWN_STATIC_FINALS = Collections.unmodifiableMap(values);
}
private static final String DURATION_OF = "Duration.of";
private static final Map DURATION_SUFFIX;
static {
Map values = new HashMap<>();
values.put("Nanos", "ns");
values.put("Millis", "ms");
values.put("Seconds", "s");
values.put("Minutes", "m");
values.put("Hours", "h");
values.put("Days", "d");
DURATION_SUFFIX = Collections.unmodifiableMap(values);
}
private final Map fieldValues = new HashMap<>();
private final Map staticFinals = new HashMap<>();
@Override
public void visitVariable(VariableTree variable) throws Exception {
Set flags = variable.getModifierFlags();
if (flags.contains(Modifier.STATIC) && flags.contains(Modifier.FINAL)) {
this.staticFinals.put(variable.getName(), getValue(variable));
}
if (!flags.contains(Modifier.FINAL)) {
this.fieldValues.put(variable.getName(), getValue(variable));
}
}
private Object getValue(VariableTree variable) throws Exception {
ExpressionTree initializer = variable.getInitializer();
Class wrapperType = WRAPPER_TYPES.get(variable.getType());
Object defaultValue = DEFAULT_TYPE_VALUES.get(wrapperType);
if (initializer != null) {
return getValue(initializer, defaultValue);
}
return defaultValue;
}
private Object getValue(ExpressionTree expression, Object defaultValue)
throws Exception {
Object literalValue = expression.getLiteralValue();
if (literalValue != null) {
return literalValue;
}
Object factoryValue = expression.getFactoryValue();
if (factoryValue != null) {
return getFactoryValue(expression, factoryValue);
}
List arrayValues = expression.getArrayExpression();
if (arrayValues != null) {
Object[] result = new Object[arrayValues.size()];
for (int i = 0; i < arrayValues.size(); i++) {
Object value = getValue(arrayValues.get(i), null);
if (value == null) { // One of the elements could not be resolved
return defaultValue;
}
result[i] = value;
}
return result;
}
if (expression.getKind().equals("IDENTIFIER")) {
return this.staticFinals.get(expression.toString());
}
if (expression.getKind().equals("MEMBER_SELECT")) {
return WELL_KNOWN_STATIC_FINALS.get(expression.toString());
}
return defaultValue;
}
private Object getFactoryValue(ExpressionTree expression, Object factoryValue) {
Object instance = expression.getInstance();
if (instance != null && instance.toString().startsWith(DURATION_OF)) {
String type = instance.toString();
type = type.substring(DURATION_OF.length(), type.indexOf('('));
String suffix = DURATION_SUFFIX.get(type);
return (suffix == null ? null : factoryValue + suffix);
}
return factoryValue;
}
public Map getFieldValues() {
return this.fieldValues;
}
}
}